Cutout switch



R. MANG CUTOUT SWITCH Oct. 14, 1958 2 Sheets-Sheet l Filed April 16, 1957 Oct. 14, 1958 R. MANG 2,856,487

CUTOUT SWITCH Filed April 16, 1957 I 2 Sheets-Sheet 2 Fig. 3

INVEIVTOE:

Patented Oct. 14, 1958 CUTOUT SWITCH Robert Mang, Paris, France Application April 16, 1957, Serial No. 653,217

Claims priority, application France April 28, 1956 6 Claims. (Cl. 200-416) This invention relates to circuit-breakers and more particularly to cutout switches and it is the chief object of this invention to provide an improved electrical apparatus designed for acting either as an ordinary switch for making and breaking a contact, or as a cutout for automatically opening the circuit when the current flowing through this circuit exceeds a predetermined value.

It is already known to construct current-limiting cutouts wherein a bimetallic control strip carries one or more movable contacts, the current flowing through this strip. This current-responsive element consists of a bimetallic strip or disc preset to a curved shape and adapted to have its curvature inverted with a snap action when heated by the Joule effect for a predetermined current strength, so as to actuate the movable contacts and open the circuit. Moreover, these cutouts comprise adequate control means acting on the current-responsive element to reclose the circuit when the cause having determined the cutout action has disappeared.

The apparatus according to this invention comprises similarly a bimetallic element which opens the circuit automatically in case of overcurrent, but it is so designed that the automatic control means for reclosing this element may also act as manual control means for moving the movable contact carried by said current-responsive ele ment so that the apparatus may operate not only as a cutout but also as a switch.

In fact, the apparatus according to this invention is characterized essentially in that the bimetallic currentresponsive element which carries a movable contact at its free end is supported in turn by a movable member mounted for tilting movement in the casing of the apparatus and adapted to be actuated by means of a sliding push-member provided with a control knob. This sliding push-member is adapted to cause the movable member and consequently the movable contact carried thereby to tilt in one or the other direction for either separating the movable contact from the fixed contact or moving the former towards the latter, this last-mentioned operation serving the purpose of reclosing the switch as a consequence either of a voluntary switch-opening movement, or of an automatic separation of the contacts due to a snap reversing of the curvature of the current-responsive element in case of overcurrent.

The movable member consists of a plate bent substantially to a U shape on the side opposite to the currentresponsive element, the latter being secured on one edge of this U shaped plate the other edge of which carries side trunnions pivoting on the casing of the apparatus.

The sliding push-member comprises on its lower face a projection located substantially between the branches of the U-shaped movable member, each end of this projection engaging a corresponding branch of the movable member to tilt same in one or the other direction according to the direction of motion of the push member.

Other features and advantages of this invention will appear as the following description proceeds with reference to the accompanying drawings illustrating diagrammatically by way of example a typical embodiment of the cutout switch of this invention and forming part of the specification.

In the drawings:

Figure l is a perspective exploded view showing the essential component elements of an apparatus according to this invention;

Figure 2 is a perspective view showing the currentresponsive element assembled with the movable member; and

Figures 3, 4 and 5 are fragmentary sectional views showing an apparatus constructed in accordance with the teachings of this invention, the control members and component elements thereof being shown in diiferent operating positions.

The apparatus illustrated in the drawings comprises an insulating base 1 carrying a pair of input and output terminals 2, 3 and a cover 4 adapted to fit over the base to form a case. This apparatus contains a bimetallic control element 5 which may consist of a strip or disc having a suitable preset curvature adapted to be reversed with a snap action when heated by the Joule effect when the current flowing therethrough attains a predetermined value. Preferably, this bimetallic element consists of a curved, dished metal disc of non-developable configuration which is formed with an annular cut-out portion so as to comprise an external annulus 5a and a central portion 512 connected by a junction zone.

The central portion 5b of the disc is secured on a lug 6a of a movable member 6 consisting of a bent, substantially U-shaped plate the branches of which extend in a. direction opposite to the disc 5. Thus, this bent plate 6 comprises two side branches 7, 8, the branch 7 being notched in its middle to form a pair of side arms, as shown. These arms are slightly inclined on the side opposite to the branch 8 and their free ends are bent back, as shown. The fixation lug 6a of the bimetallic disc corresponds to the notch formed in the branch 7, so that the disc is secured in the vicinity of one of the corners of this movable member. Adjacent to the other corner of this movable member are a pair of lateral trunnions 9 pivotally mounted in suitable bearing-forming cavities of the base 1, so that the movable member may tilt freely therein.

The disc 5 carries a movable contact 10 on its external annulus 50, on the side opposite to the zone where this annulus is connected to the central portion 5b, this zone being adjacent to the trunnions 9, as shown in Fig. 2. A fixed contact 11 is provided under the movable contact 10. This fixed contact is secured substantially centrally of a flexible strip 12 constituting an electrical connection between the terminal 2 and the fixed contact. One end of this strip 12 is clamped between the terminal and the base 1, and the other end has screwed y through it a micrometric'screw 13 engaging the base 1 so that the pressure between the contacts 10, 11 may be adjusted with precision by screwing in or out the screw 13.

The apparatus also comprises a push-member 14 adapted to actuate the movable member 6. This pushmember 14 is slidably mounted in a frame 15 secured on the base 1 and carries on its upper face a control button 16 projecting externally from the cover 4 of the apparatus through a suitable slot. The lower face of the sliding push-member comprises a projection 17 lying between the branches 7 and 8 of the movable member 6 when the component elements of the apparatus are in their inoperative position (see Fig. 5). As the lateral branch 7 of the movable member 6 is divided into two arms, the projection 17 of the push-member is also divided into two corresponding portions disposed on either side of a central portion 18. This central portion comprises on the other hand a cavity adapted to receive a coil spring 19 hearing with one end against the aforesaid frame 15 and with its other end the push-member on the side of the branch 8 of the movable member.

. As already set forth, hereinabove the control members of e pparatu are inoperative in e P on shown in Fig. 5. In fact, the spring 19 urges the push-m mber 14 and the latter acts through its projection 17 on the branchtt of the movable member so as. to tilt same about its trunnions. 9... The disc 5" is thus. lifted, so. that the movable contact is held away from the, fixed contact 11.. Of course, the disc, in its. normal position has its concavity on its lower face, that is, towards the fixed contact 11. i

To close the cutout switch it is sufiicient to move the push-member 14in the direction to compress the spring 19., that is, tothe left when considering the Figure 3. During this. movement, the push-member engages through its projection 17 the two arms 7 of the movable member, thereb-ytiltiug the latter to theposition in which the contacts. 10: and 11 are closed; When the push-member 14 is pushed home against the spring 19 its projection 17 overlies the curvedends of the arms 7 of the movable member, suitable notches 20 being provided for receiving these arm ends. As the disc 5 is in its normal position and .ensuresv a. sufficient pressure between the contacts, thisipressure is transmitted to the end of. the arms 7 of themovable-member which are thus held in the notches 2010f the push-member. Consequently, the latteris releasiblyheldin this position against the pressure of the compression spring 19 (see Fig. 3-).

However, the locking action just described is of such nature that it is possible nevertheless toopen the switch by moving the push-member in the opposite direction, that is, to the right when considering Figs. 3 to 5, the arms 7' being easily released from the notches 20 whereafter-the-projection 17 of the push-member engages the opposite branch 8 of the movable member to tilt same and move the contact 10 away from the fixed contact 11 (see Fig. 5-)--.

This'release ofthe arms 7- from the notches 20 occurs similarly but automatically when the curvature of the disc- 5 is reversed by the heatdeveloped by the Joule effect dueto an overcurrent in the circuit. The minimum overcurrent value required to reverse the curvature of the disc 5 in a giventime period may be pro-adjusted by means of the screw 13. When the disc is reversed the external annulus 5a thereof is raised and causes a snap movement ofthe movable contact 10 away from the. fixed contact 11. The central portion 5b on the other hand tends to move very slightly downwards and as the discdoesnot' exert-any pressure on the arms 7 the spring 19 moves the push-member to the position shown in In this positionthe curvature of the disc 5 is still reversed, of course. The closing of-the cutout switch will occur only when the disc has actually been reversed.

Now two difierent types of bimetallic discs may be used in this cutout switch:

(1) The so-called thermostatic discs which resume automatically their initial. position when their temperature has, fallen to a value approximating the ambient value;

(2) The so-called non-thermostatic discs which cannot resume their initial shape, even when the temperature has resumed its normal value, unless they are reversed by exerting a mechanical effortthereon.

Let us assume that the cutout'switch of this invention isprovided with a thermostatic disc. A few moments after its reversing when the temperature of the disc has fallen toa suflicient degree, the disc. will automatically resume its, initial position.- Nevertheless, the cutout switch remainsin its. openposition (Fig. 5).

Now one of the essential advantageous features of the apparatus of this invention willbecome apparent; asthe:

disc resumes automatically its initial shape or position, it will not reclose a circuit in which abnormal operating conditions still prevail. In fact, to reclose the circuit, the switch must be actuated by moving the push member 14 against the resistance of the spring 19. Thus, the user may actuate this push member after having eliminated the cause of trouble from the circuit.

Now let us assume that the cutout switch is equipped with a no-n-thermostatic disc. After a short-circuit, as the disc does not resume its initial shape when the ambient temperature is restored therein, a mechanical actlon must be applied to reset the disc. Now this action may be effected by the spring 19 itself.

Reference will now be made to Fig. 4 showing the apparatus after the release thereof due to an overcurrent in the circuit, and before the disc has cooled down to normal temperature.

The spring 19 in theopen position of the device exer-ts a pressure through. the medium. of. the. push member 14 against'the branch .8 ofv the. movable member 6 and therefore. against thev centraL portion 5b of the disc. Now the portion of the annulus 5a. which carries the movable contact Lil-engages. the corresponding portion of the insulating fixed. wall 21. Thus, when the disc' has cooled sufficiently thepressure of spring. 1 is sufiicient to reverse the curvature. ofthe disc so that the latter resumes its initial shape.

If. desired and. without departingfrom the purpose of the. invention it is. also possible to provide a cutout switch wherein the bimetallic disc reset not by the springbut by a voluntary. manual .or other action produced on the push-member 14 to-strongly-urge the projection:17 there.- of against. the branch 8 of the movable member. 6. In this case, thespring 19. may beof relatively moderate forceas the disc curvature is not reversed by the spring;

It may happenthat, due to an accidental or faulty-con dition arising in the electrical circuit, the switch is reclosed on a short circuit. Inthis case the bimetallic disc would'be-under defective operating conditions. In fact, a normaloperationof the disc Wouldnecessitate that the contacts 10, 1-1 be under a minimum pressure when an overcurrentoccurs. Besides, this pressure must be adjusted to a. well defined value. This adjustment isnor mally effected by screwing in or out the micrometric screw: 13; Consequently, it isevident that when the switchissclosed the current beginsto how while the contactsare subjected but to a very low pressure differingverymuchfrom the adjustment pressure of the disc 5; Thus, under these-conditions thebreaking power of the disc-is relatively reduced.

Toavoid this-inconvenience, the bimetallic disc or strip of any form equipping the apparatus may be provided with a suitablydesignedstop so mounted as'to constantly keep the disc orstrip under the requisit'epressure and'in the proper shape obtaining when the contacts are normally engaging eachother'during the closingof the apparatus;

In the case of adisc 5 as illustrated-in this example theaforesaid stopconsists of a transverse strip 22 which may be a metal'strip; This strip is secured by its'middle on thfllOWCI face of thecentral portion" 5b of the disc and extends at right angles to the radius passing through the contact 10; Thus, this transversestrip will urge the sides of the annulus 5a of the'dis'cupwa-rdsso that the latterwill undergo a-changein' shape-which is as pro nounced as that to which it is subjected when it exerts the normal adjustment pressure-onthe contacts.

Thus,- if" the switch is closed during a short-circuit, the disc-willalreadybein conditions very close to its optimum adjust-mentconditionswhen the current begins to flow thereth-rough: Therefore, the breaking power of the cutoutris not'impaired.

Preferably, the-strip-22is'secured on the central. portion 5a-of the disc by'thesame rivet 23 which secures the -lug- 6a of the movable-member, this river 'also fastening theaflexible connection 24- from the -centre 5b of the disc to the terminal 3. According to a specific feature, this flexible connection 24, which may advantageously consist of a copper blade, is adapted to exert a springlike action and causes through its curved shape the movable member to be urged in such a position that the contacts 10, 11 are held away from each other during the very short time required for the push member 14 to move from one position to the other position.

Of course, the apparatus of this invention is not limited to the embodiment illustrated and described herein, as many modifications may be brought thereto without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. A cutout switch comprising an insulating case provided with an input terminal and an output terminal, a bimetallic current-responsive dished element of the curvature snap-reversing type which is connected to one of said terminals, a movable contact on said bimetallic element, at fixed contact provided in said case in front of said movable contact and connected to the other terminal, a tilting support pivoted in the case and supporting the said bimetallic element, a push-member slidably mounted in said case and adapted to actuate said support in one and the other direction, a spring urging said push member against said support on the side opposite to said movable contact of said bimetallic element, releasable locking means provided on said support and said push member respectively, said means being adapted when eoacting together on the one hand to keep said support in its tilted position with said movable contact engaging said fixed contact, and on the other hand to hold said push member against motion on the spring side, whereby said spring is held in its compressed condition.

2. A cutout switch comprising an insulating case provided with an input terminal and an output terminal, a bimetallic current-responsive dished element of the curvature snap-reversing type which is connected to the other terminal, a movable contact on said bimetallic element, a fixed contact in said case which registers with said movable contact and is connected to said other terminal, a tilting, substantially U-shaped support carrying said himetallic element and having its branches bent on the side opposite to said bimetallic element, said bimetallic element being secured on one side of said support, the edge on the side opposite to said support comprising pivot means through which said support is pivoted on said case, a push member slidably mounted in said case to register with said support and on the same side as said bent branches, said push member being adapted to actuate either end of said support, a spring urging said push member in the direction of said first end of said support which is on the side opposite to said movable contact of said bimetallic element, locking means on said other end of said support and said push member respectively, said means being adapted when coacting together on the one hand to keep said support in its tilted position wherein the movable contact of said bimetallic element engages said fixed contact, and on the other hand to hold saidpush member against motion on the spring side, whereby said spring is held in its compressed condition.

3. Cutout switch as set forth in claim 2, wherein the other bent end of said support is notched to a U-shape,

locking means provided on said end of the support and on said push member consisting on the one hand of a bent end portion formed on each arm of said end and on the other hand of a notch formed in said push member.

4. Cutout switch as set forth in claim 2, wherein said bimetallic element is connected to the corresponding terminal through a flexible conductor constituting a spring of moderate strength which constantly urges said movable contact of said bimetallic element away from said fixed contact.

5. Cutout switch as set forth in claim 2, comprising in addition in said case a partition of insulating material which registers with said movable contact of said bimetallic element on the side opposite to said fixed contact, said insulating partition being adapted to act as a stop for said movable contact when the curvature of said himetallic element is reversed.

6. A cutout switch comprising an insulating case pro vided with an input terminal and an output terminal, a bimetallic current-responsive dished element adapted to have its curvature reversed when the current flowing therethrough exceeds a predetermined value, said bimetallic disc being connected to one of said terminals, a movable contact on the edge of one side of said bimetallic disc, a fixed contact in said case which registers with said movable contact and is connected to the other of said terminals, a U-shaped tilting support carrying said bimetallic disc by the centre of said disc, the branches of said U-shaped support being bent on the side opposite to said bimetallic disc, the edge of said support which is positioned on the side opposite to said movable contact of said bimetallic element carrying the pivot means through which said support is pivoted on said case, a push member slidably mounted in said case which registers with said support and is positioned on the same side as the bent end portions of said support, said push member being adapted to actuate either end of said support, a spring urging said push member in the direction of the first end of said support which is on the side opposite to said movable contact of said bimetallic disc, locking means provided on the other end of said support and on said push member respectively, said locking means being adapted when co-acting together on the one hand to hold said support in its tilted position wherein said movable contact of said bimetallic disc engages said fixed contact and on the other hand to hold said push member on the spring side, whereby said spring is held in its compressed condition.

References Cited in the file of this patent UNITED STATES PATENTS (Addition to No. 1,038,547) 

